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		<title>three.js webgl - interactive cubes (gpu)</title>
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		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> webgl - gpu picking
		</div>

		<div id="container"></div>

		<script type="module">

			import * as THREE from '../build/three.module.js';

			import Stats from './jsm/libs/stats.module.js';

			import { TrackballControls } from './jsm/controls/TrackballControls.js';
			import * as BufferGeometryUtils from './jsm/utils/BufferGeometryUtils.js';

			let container, stats;
			let camera, controls, scene, renderer;
			let pickingTexture, pickingScene;
			let highlightBox;

			const pickingData = [];

			const pointer = new THREE.Vector2();
			const offset = new THREE.Vector3( 10, 10, 10 );

			init();
			animate();

			function init() {

				container = document.getElementById( 'container' );

				camera = new THREE.PerspectiveCamera( 70, window.innerWidth / window.innerHeight, 1, 10000 );
				camera.position.z = 1000;

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0xffffff );

				pickingScene = new THREE.Scene();
				pickingTexture = new THREE.WebGLRenderTarget( 1, 1 );

				scene.add( new THREE.AmbientLight( 0x555555 ) );

				const light = new THREE.SpotLight( 0xffffff, 1.5 );
				light.position.set( 0, 500, 2000 );
				scene.add( light );

				const pickingMaterial = new THREE.MeshBasicMaterial( { vertexColors: true } );
				const defaultMaterial = new THREE.MeshPhongMaterial( { color: 0xffffff, flatShading: true, vertexColors: true, shininess: 0	} );

				function applyVertexColors( geometry, color ) {

					const position = geometry.attributes.position;
					const colors = [];

					for ( let i = 0; i < position.count; i ++ ) {

						colors.push( color.r, color.g, color.b );

					}

					geometry.setAttribute( 'color', new THREE.Float32BufferAttribute( colors, 3 ) );

				}

				const geometriesDrawn = [];
				const geometriesPicking = [];

				const matrix = new THREE.Matrix4();
				const quaternion = new THREE.Quaternion();
				const color = new THREE.Color();

				for ( let i = 0; i < 5000; i ++ ) {

					let geometry = new THREE.BoxGeometry();

					const position = new THREE.Vector3();
					position.x = Math.random() * 10000 - 5000;
					position.y = Math.random() * 6000 - 3000;
					position.z = Math.random() * 8000 - 4000;

					const rotation = new THREE.Euler();
					rotation.x = Math.random() * 2 * Math.PI;
					rotation.y = Math.random() * 2 * Math.PI;
					rotation.z = Math.random() * 2 * Math.PI;

					const scale = new THREE.Vector3();
					scale.x = Math.random() * 200 + 100;
					scale.y = Math.random() * 200 + 100;
					scale.z = Math.random() * 200 + 100;

					quaternion.setFromEuler( rotation );
					matrix.compose( position, quaternion, scale );

					geometry.applyMatrix4( matrix );

					// give the geometry's vertices a random color, to be displayed

					applyVertexColors( geometry, color.setHex( Math.random() * 0xffffff ) );

					geometriesDrawn.push( geometry );

					geometry = geometry.clone();

					// give the geometry's vertices a color corresponding to the "id"

					applyVertexColors( geometry, color.setHex( i ) );

					geometriesPicking.push( geometry );

					pickingData[ i ] = {

						position: position,
						rotation: rotation,
						scale: scale

					};

				}

				const objects = new THREE.Mesh( BufferGeometryUtils.mergeBufferGeometries( geometriesDrawn ), defaultMaterial );
				scene.add( objects );

				pickingScene.add( new THREE.Mesh( BufferGeometryUtils.mergeBufferGeometries( geometriesPicking ), pickingMaterial ) );

				highlightBox = new THREE.Mesh(
					new THREE.BoxGeometry(),
					new THREE.MeshLambertMaterial( { color: 0xffff00 }
					) );
				scene.add( highlightBox );

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				container.appendChild( renderer.domElement );

				controls = new TrackballControls( camera, renderer.domElement );
				controls.rotateSpeed = 1.0;
				controls.zoomSpeed = 1.2;
				controls.panSpeed = 0.8;
				controls.noZoom = false;
				controls.noPan = false;
				controls.staticMoving = true;
				controls.dynamicDampingFactor = 0.3;

				stats = new Stats();
				container.appendChild( stats.dom );

				renderer.domElement.addEventListener( 'pointermove', onPointerMove );

			}

			//

			function onPointerMove( e ) {

				pointer.x = e.clientX;
				pointer.y = e.clientY;

			}

			function animate() {

				requestAnimationFrame( animate );

				render();
				stats.update();

			}

			function pick() {

				//render the picking scene off-screen

				// set the view offset to represent just a single pixel under the mouse

				camera.setViewOffset( renderer.domElement.width, renderer.domElement.height, pointer.x * window.devicePixelRatio | 0, pointer.y * window.devicePixelRatio | 0, 1, 1 );

				// render the scene

				renderer.setRenderTarget( pickingTexture );
				renderer.render( pickingScene, camera );

				// clear the view offset so rendering returns to normal

				camera.clearViewOffset();

				//create buffer for reading single pixel

				const pixelBuffer = new Uint8Array( 4 );

				//read the pixel

				renderer.readRenderTargetPixels( pickingTexture, 0, 0, 1, 1, pixelBuffer );

				//interpret the pixel as an ID

				const id = ( pixelBuffer[ 0 ] << 16 ) | ( pixelBuffer[ 1 ] << 8 ) | ( pixelBuffer[ 2 ] );
				const data = pickingData[ id ];

				if ( data ) {

					//move our highlightBox so that it surrounds the picked object

					if ( data.position && data.rotation && data.scale ) {

						highlightBox.position.copy( data.position );
						highlightBox.rotation.copy( data.rotation );
						highlightBox.scale.copy( data.scale ).add( offset );
						highlightBox.visible = true;

					}

				} else {

					highlightBox.visible = false;

				}

			}

			function render() {

				controls.update();

				pick();

				renderer.setRenderTarget( null );
				renderer.render( scene, camera );

			}

		</script>

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